The invention relates generally to automated switches, and more particularly, to an automated optical switch suitable for use in a communications network. In one embodiment, ferrules having optical fibers disposed therein are optically connected directly through a mating plate having a plurality of precision alignment holes. In another embodiment, optical fibers are optically connected directly through a mating plate having high precision alignment holes. In yet another embodiment, a method of increasing the coupling density of an automated optical switch is provided wherein ferrules having optical fibers disposed therein are optically connected directly through a mating plate having a plurality of precision alignment holes. In still another embodiment, a method of increasing the coupling density of an automated optical switch is provided wherein optical fibers are optically connected directly through a mating plate having a plurality of precision alignment holes.
It is common practice to use automated optical switches in a communications data center. Automated optical switches can also be used in the central office of a telecommunications network to replace the conventional “cross-connect” or “patch” panel of an optical distribution frame, and thereby reduce operating expenses. The most efficient robotic automated optical switch currently available for use in a telecommunications central office can accommodate only 180×180 non-blocking connections on a 19 inch (48.3 cm) wide rack having 20 cm high bays, which can practically be cascaded to a maximum of around 1000×1000 non-blocking connections. In a “non-blocking” optical switch any of the input optical fibers can be optically connected to any of the output optical fibers, provided that each input optical fiber is connected to only one output optical fiber. The typical central office, however, currently requires on the order of 10000×10000 connections. Furthermore, the cost-per-connection of an existing robotic automated optical switch is exceedingly high for fiber-to-the-home (FttH) networks.
Examples of known robotic automated optical switches are shown and described in U.S. Pat. No. 6,859,575 B1 and International Publication No. WO 2006/054300 A2 of International Application No. PCT/IL2005/001220, the disclosures of which are incorporated herein by reference. These known optical switches (referred to as optical crossbar switches) optically couple the end of one of a plurality of first (i.e. input) optical fibers each mounted to a different carriage moveable along a predetermined trajectory with the end of one of a plurality of second (i.e. output) optical fibers. A motor is configured to translate the moveable carriage of the first optical fiber in the predetermined trajectory to align the first optical fiber with one of the plurality of second optical fibers. The motor also moves a slack-control carriage to take up slack in the first optical fiber generated by movement of its carriage in the predetermined trajectory.
Automated optical switches based on micro-electro-mechanical systems (MEMS) also are not suitable to replace the optical coupling equipment on an optical distribution frame in a central office of a telecommunications network since such switches fail during a power interruption. In short, the currently available automated optical switches for use in a central office of a telecommunications network do not provide a sufficient number of non-blocking optical connections, are not cost-efficient to operate, or fail when there is an interruption of electrical power to the switch.
Accordingly, there exists an unresolved need for an improved automated switch. There exists a more specific need for an improved automated optical switch suitable for use in a communications network. There exists a still more specific need for an automated switch that provides a sufficient number of non-blocking connections, is cost-efficient to operate, and does not fail when there is an interruption of electrical power to the switch.